Many manufacturing processes can induce residual stresses in components. These residual stresses influence the mean stress during cyclic loading and so can influence the fatigue life. However, the initial residual stresses induced during manufacturing may not remain stable during the fatigue life. This paper provides a broad and extensive literature survey addressing the stability of surface and near-surface residual stress fields during fatigue, including redistribution and relaxation due to static mechanical load, repeated cyclic loads, thermal exposure and crack extension. The implications of the initial and evolving residual stress state for fatigue behaviour and life prediction are addressed, with special attention to fatigue crack growth. This survey is not a critical analysis; no detailed attempt is made to evaluate the relative merits of the different explanations and models proposed, to propose new explanations or models or to provide quantitative conclusions. Primary attention is given to the residual stresses resulting from four major classes of manufacturing operations: shot peening and related surface treatments, cold expansion of holes, welding and machining.

A literature survey on the stability and significance of residual stresses during fatigue

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Methods for the prediction of fatigue delamination growth in composites and adhesive bonds: A critical review

Review on fracture and crack propagation in weldments - A fracture mechanics perspective

Control of welding residual stress for ensuring integrity against fatigue and stress–corrosion cracking

Book reviewProgress in Science and Engineering of Composites: (2 volumes.) Edited by T. Hayashi, K. Kawata and S. Umekawa. 1982. North-Holland Publishing Co., Amsterdam. civ + 1890 pp. ISBN 0 444 86558 6. Price: US$212·75; Dfl. 500·00

Fatigue crack growth in residual stress fields: experimental results and modelling.

— The paper discusses the results of fatigue crack growth rate tests conducted in the presence of residual stresses. Three different residual stress distributions, obtained by laser welds, were employed in order to characterize the crack propagation behaviour under different conditions, producing either an increase or a reduction of the stress intensity factor due to external loads. Test results are analysed by means of a non-linear numerical model (based on the weight function method) and a knowledge of the fatigue crack growth properties of the base material, free from residual stresses. The results of the analysis are discussed with reference to experimental trends, in order to clarify the predictive capabilities of the method and aspects needing further investigation.

Fatigue crack growth in residual stress fields : experimental results and modelling

A hybrid drive assembly (1) for a vehicle having at least one drive wheel (2),the drive assembly including an internal combustion engine (3); a transmission unit (5) interposed between a drive shaft (4) of the internal combustion engine (3) and a propeller shaft (6) connected angularly to the drive wheel (2), and in turn including a continuously variable transmission (7) having a drive pulley (10) connected angularly to the drive shaft (4) and a driven pulley (11), and a centrifugal clutch (8) having a hub (20) connected to the driven pulley, and a driven bell (26) connected to the propeller shaft (6); and an electric machine (32) having a rotor (35) integral with the bell (26) of the centrifugal clutch (8) . The drive assembly (1) is controlled by a control unit (38), in response to a number of input signals (Ss, Sa, Sf), in a number of operating modes including an all-combustion propulsion mode, an all-electric propulsion mode, a first hybrid propulsion mode wherein the internal combustion engine (3) and the electric machine (32) are connected in series, and a second hybrid propulsion mode wherein the internal combustion engine (3) and the electric machine (32) are connected in parallel.

Hybrid drive assembly for a vehicle, in particular a scooter

— An overview is presented of studies conducted at the University of Pisa on the Weight Function technique as applied to Fatigue Crack Grown analysis. The fundamental theoretical aspects of the technique are summarised, discussing some recent methods for the determination of the Weight Function. The application of the technique to non-linear (contact) problems and to the evaluation of the crack tip stress field is also discussed. It is shown that the Weight Function method allows one to efficiently consider many crack propagation problems, some examples of which are provided.

Weight functions applied to fatigue crack growth analysis

The paper deals with the development of a numerical method for determining Weight Functions in two-dimensional problems. After a short review of some recent numerical techniques an original approach is presented. The method is based on Finite Element calculations with coarse meshes and on the knowledge of some values of the Stress Intensity Factor for one reference loading condition. The validity of the method is demonstrated for a theoretical case and its accuracy and suitability are discussed with reference to practical applications.

Emilio Vitale

Papers

Fatigue crack growth in residual stress fields: experimental results and modelling.

Fatigue crack growth in residual stress fields : experimental results and modelling

Hybrid drive assembly for a vehicle, in particular a scooter

Weight functions applied to fatigue crack growth analysis

A numerical approach for determining weight functions in fracture mechanics